Abrasive article



w. K. VAN ORMER Erm. 2,770,928

Nov. 20, 195.6

ABRASIVE ARTICLE F'iled June 15, 1951 INVENTOR.

I/VILLAM K. VAN ORME?? JOSEPH B.AUST

ATTORN N0V- 20, 1956 w. K. VAN ORMER ErAL 2,770,928

ABRAsIvE ARTICLE Filed June 15, 195] 3 Sheets-Sheet 2 IN V EN TOR.

WILLIAM K. VAN ORME R JOSEPH B. AUST ATTO E Y NOV- 20, 1956 w. K. VANORME-:R ErAL 2,770,928

ABRAsIvE ARTICLE Filed June l5. 1951 5 Sheets-Sheet .'5

GRAMS OF' STOCK REMOVED .PER 3 MINUTE INTERVAL.

l 2124 Z7 30 33 36 39 42 45 46 5l 54- TIME JN MINUTES FIG. 9

INVENTOR. WILLIAM K VAN ORME'R JOSEPH .B.AU.ST

ATTOR E Y United States Patent O ABRASIVE ARTICLE William K. Van Omerand Joseph B. Aust, Niagara Falls, N. Y., assignors to The CarborundumCompany, Niagara Falls, N. Y., a corporation of Delaware Application`lune 15, 1951, Serial No. 231,744

9 Claims. (Cl. 51-195) This invention relates to abrasive articles ofmanufacture such as abrasive discs, belts, bands, wheels and other formsof abrasive articles.

Abrasive products can be usually classified or identified with one orthe other of two broad classifications of abrasive products, namely,those belonging in the field of bonded abrasive bodies of the grindingwheel type consisting of a substantial bulk of abrasive grains and bondand those belonging in the field of coated abrasives of the sandpapertype in which a substantially single layer of abrasive grains isadhesively secured to a flexible backing material. Each of these typesof abrasive products has certain advantages not possessed by the othertype as well as certain limitations.

ln the manufacture of bonded abrasive articles of the grinding wheeltype the individual abrasive particles are bonded together by means ofan organic or inorganic binder, the desired body being formed by mixingthe abrasive grains and bond together to form a molding mixture which isthen pressed or otherwise formed into a solid mass of material of thedesired shape. The article is then heated or fired to mature the bondand form the desired solidified rigid mass which is then usually dressedto size. The resulting rigid body of abrasive material is eithercemented or bolted to a steel backing plate or other support or mountedconventionally on a machine shaft or spindle with appropriate bushingsor flanges and operated at relatively high speeds to perform the desiredabrading operation.

The strength of the bonded abrasive body is dependent to a great extentupon the strength of the fired or cured bonding material and iscontrolled within certain limits by the amount by weight and volume ofthe bonding material in relation to the total weight and volume of thebonded abrasive body. The resultant article is rigid, non-flexible andnormally quite brittle and therefore requires careful testing beforeuse. Precautions must be taken in respect to its mounting and use inorder to provide the maximum degree of safety during its operation atrelatively high speeds. The inherent rigidity, accompanied as it is by arelatively high degree of brittleness or fragility, greatly restrictsthe scope of application of such articles.

However, products of the grinding wheel type offer the prime advantageof having relatively long operating lives. A further advantage is therelatively high rate of breakdown or expendibility which can betolerated in view of the availability of a substantial amount ofabrasive material in the article, and is often desirable to promote ahigh rate of cut. The rate of wear-ability or breakdown is dependentlargely upon the bond structure of the body which sometimes is renderedporous by the incorporation of filler materials which are volatilized orburned off during the maturing of the bond, particularly in wheels whichare designed for fast cutting operations and relatively rapid wheelbreakdown is desired. A grinding wheel which cuts fast is referred to asa sof wheel and wears away relatively rapidly. However, pro- 2,770,928Patented Nov. 20, 1956 ICC motion of the porosity and rate of cut of aWheel in the above manner has its limitations since it is accompanied bya lowering of wheel strength and life.

In contrast to abrasive products of the grinding wheel type which areextremely hard, rigid and inflexible in character and have relativelylong operating life, abrasive articles of the coated type consist of asubstantially single layer of abrasive grits adhesively secured to aexible backing and, as a result of the relatively small amount ofabrasive particles available in the article, the products have arelatively short life with a very high rate of stock removal.Consequently, the cost of various backing materials in such productsmust be kept to a minimum in order that the overall cost of the productdoes not become so great as to nullify the advantages gained from theflexibility and versatility of the products derived therefrom. Attemptsto extend or prolong the life of coated abrasive products by the use ofheavier coatings of abrasive material in conjunction with the use ofextra heavy or more durable backings have never proven satisfactorysince such products have tended to become dull and glazed regardless ofcoating thickness and often break down excessively due to the prematureseparation of the abrasive coating from the backing.

It is an object of the present invention to provide abrasive articleswhich combine to a large extent the long operating life and durabilityof abrasive articles of the grinding wheel type with certain elements ofversatility and flexibility previously found only in abrasive articlesof the coated abrasive or sandpaper type.

It is a further object to provide a type of abrasive article which canbe made with any desired degree of rigidity or flexibility.

lt is a further object to provide abrasive products having a relativelysubstantial mass of abrasive material embodied in the article withouttotal loss of flexibility characteristics.

It is a still further object to provide an abrasive product in which asubstantial mass of bonded abrasive material is embodied in the articleand secured to a supporting structure in such a manner that the abrasivemass is substantially fully expendable without premature disruption ordislocation from its support.

These and other objects and advantages accruing from the presentinvention will become apparent as the description proceeds.

In order that the invention may be more fully understood, reference ismade to the drawings which are offered by Way of illustration only, arenot intended to restrict the invention in any way to the specificarticles shown, and in which,

Figure l is a top plan view of an abrasive disc made in accordance withthe present invention,

Figure 2 is a vertical, diametrical cross-sectional view through theline 2--2 of Figure l,

Figure 3 is a vertical, sectional view through an endless abrasive beltmade in accordance with the present invention,

Figure 4 is a vertical, diametrical sectional view through a cup-shapedabrasive wheel made in accordance with and embodying various features ofthe present in vention,

Figure 5 is a view similar to that of Figure 2 of a modified form ofabrasive disc embodying features of the present invention,

Figure 6, likewise similar to Figure 2 in view, shows a still furthermodification of the invention,

Figure 7 shows certain structural details of the textile anchoring'layer and vertical pile members embodied in the disc structure shown inFigure 2 and the belt structure shown in Figure 3,

Figure 8 shows a top plz-1n view of a modified form of abrasive disc;and

Figure 9 is a graph showing graphically the grinding results obtainedwith products of the present invention as compared to conventionallyprepared coated abrasive articles and bonded articles heretofore usedfor the same purpose.

We have found that abrasive articles such as abrasive discs, wheels,belts, bands and other shapes can be made in accordance with andembodying various features of the present invention so as to combine thelong life and durability characteristics in many respects found inabrasive articles of the grinding wheel type with that lexibili-ty anddependent versatility of application heretofore found only in coatedabrasive products. The inventiort is not intended to be limited to thespecific articles illustrated in the various figures of the drawingsince it is applicable to the construction of numerous forms of abrasivearticles commonly known and used in the art including such articles as:

l. Abrasive bands and belts for operating over either drums or pulleysand back-up plates,

2. Abrasive discs for use with or without auxiliary backup supports,

. Cup wheels,

. Annular type snagging wheels,

. Ring and recessed wheels of various types and sizes,

. Flexible polishing wheels; and

. Blocks and shapes adapted for use on expanding chucks such as thoseshown in U. S. Patents Nos. 2,207,439 and 2,264,589.

Abrasive articles of the present invention, regardless of their specificform or shape, are provided with a layer of bonded abrasive material ofsubstantial thickness and are further characterized by having amultitude of spaced pile members extending through the mass of bondedabrasive substantially to the grinding surface with the lower ends ofthe pile members anchored in the base layer of the article in any one ofa variety of ways. The article is further characterized in that thebonded abrasive mass provides a substantially continuous or solidgrinding surface with no deep, irregular depressions` between the spacedpile members contained therein. The. reinforcing pile members can be ofany material of organic or inorganic nature and can be single ormultiple strands, either straight, crimped or looped members, and eitherlamentary or fibrous in character. For example, the spaced pile memberscan be composed of various textile fiber cord materials, such as cordedcotton fibers, corded wool fibers or other animal or vegetable fibers,or lilamentary materials. The pile members can also be composed of anyof the numerous synthetic organic materials now available in eitherfibrous or lamentary form, such as the polyamide fibers or filamentsknown and sold by E. I. du Pont de Nemours and Company of Wilmington,Delaware, under the generic trade name of nylon, the vinylidine chloridepolymers in fibrous or filamentary form such as those known and sold byDow Chemical Company of Midland, Michigan, under the trade name of Saranfibers or filaments, or by Firestone Plastic Company of Pottstown,Pennsylvania, under the trademark name of Velon fibers or filaments, thezein protein fibers known under the trademark name of Vicara fibers andsold by the Virginia-Carolina Chemical Corporation, Fiber Division ofTaftville, Connecticut, the viscose rayon fibers sold by E. I. du Pontde Nemours and Company under the trade name of Cordura fibers, or thepolyacrylonitrile fibers sold by the same company under the trade nameof Orlon" fibers. or other organic resinous fibrous or tilamentarymaterials. The pile members can also consist of an inorganic filament orber such as a cord or rope composed of glass or rock wool fibers orfilaments such as those known and sold by Owens-Corning FiberglasCorporation of Toledo, Ohio as Fiberglas products.

These pile members which extend through thc mass of granular abrasivematerial and are an essential feature of articles made in accordancewith the present invention are anchored at their lower ends in any oneof a variety of ways. For example, the pile members can be secured inthe base of the bonded abrasive layer by being set or anchored in asolidified layer of adhesive or binder which is preferably of thepermanently liexible or resilient type such as a rubber base adhesive ora coagulated latex adhesive composition. Also various resinous bindersof a naturally and permanently flexible type, or a resinous bond whichretains its strength under and after mechanical flexing, can be used.The anchoring layer of the article instead of consisting of a layer ofadhesive or binder may be, and preferably is, constructed of one or morecourses of interwoven warp or braid strands of textile fibrous materialwhich is in turn reinforced and held together by being impregnated witha suitable adhesive, usually of the resilient type, such as a latex orrubber base adhesive composition. Where reference is made to the use ofa latex or rubber base adhesive in the anchoring layer it is intended toinclude` not only natural rubber latex or natural rubber base adhesives,but also those various synthetic latices or rubber compositionsavailable such as the butadiene type synthetic rubbers, polychloroprene,and the like. When a layer of textile material is used in the anchoringlayer the vertical pile members are anchored therein, such as by beinglooped through one or more of the courses of warp strands with the freeends of the vertical pile members extending or protruding above thefia-t surface of the anchoring layer into the bonded abrasive mass whichis superimposed thereon. Another mannel: of providing a plurality ofspaced, vertical pile members anchored in a warp or braid strand headingor base is by interweaving a. continuous cord or strand through one ormore courses of the base layer with loose loops of the cord or strand`pulled up and projecting in a loo-p above thev upper face of the` baselayer at selected intervals. This anchoring layer is usually, althoughnot necessarily, backedup or supported by a further backing layer offlexible nature such as a rubber or latex impregnated sisal fiberbacking, a thin sheet oli spring steel, vulcanized fiber backing, or thelike.

A further and specific modification of the present invention consists inthe provision of an article of the above-described type in which acombination of vegetable or anirnai pile members with pile members of amore heat resistant character, such as pile members of syntheticresinous material such as nylon" or "Saran" are incorporated within thebonded abrasive layer. Also, combina-tions of any organic fiber can bcused in conjunction with inorganic glass or mineral fibers. The ratio ofanimal or vegetable fibers or other organic fiber pile members of lowheat resistance to Velom "nylon, glass or other more heat-resistant pilemembers can range all the way from 5% to 95% of one to 95% to 5% of theother, or any intermediate combination o1 tw'o or more fibrous orflamentary materials. During thel cure of' an article embodying acombination of two or more materials as pile members the less heatresistant pile members disintegrate to provide relatively weak areas iirthe' bonded abrasive mass whereby those arcas of the. overall structuretend to break dcwn more rapidly than adjoining areas. The remainingfibers et more heat resistant character break` down later during thegrinding` operation without interfering. with the cutting ability of thearticle although at the same time they would remain in the body of theabrasive mass as a reinforcing and strengthening element. By the use ofsuch composite mixtures of vertical pile members it is possible toprovide a wide range of different desirable cutting characteristicsdepending upon the type and condition of use to which the article is tobe put.

In practicing the invention, any of the abrasive materials in common usemay be employed, such as granular silicon carbide, diamonds, boroncarbide, fused aluminum oxide, flint, corundum, emery, rouge and similarsubstances. Another specific, and relatively new, product which can beused as the abrasive material in articles of the present invention is afoam, or cellular, glass in granulated form. Regardless of the kind ofabrasive used, the size of the abrasive particles may vary from thefinest polishing or buffing powders to the coarser grit sizes used ingrind- The abrasive particles can be bonded with any suitable bond whichcan be matured at temperatures which will not destroy the vertical pilemembers which are to remain in the finished article as a permanent partthereof and which function to preserve the integrity of the article overits intended life or until the abrasive layer has been usefullyexpended. Very satisfactory results have been obtained usefullyexpended. Very satisfactory results have been obtained with the use ofthermosetting phenolic condensation product resins, including thosespecifically set forth later herein in connection with the variousexamples. However, other organic binding materials, all of which can bemodified by the inclusion of suitable catalysts or vulcanizers, inertand reactive fillers, and other modifying agents as desired, can beused.

Among the organic resins which can be used are melamine-formaldehyderesins and analogs thereof, ureaformaldehyde resins and analogs thereof,thiourea-formaldehyde resins and analogs thereof, furane resins,anilineformaldehyde resins, thermosetting alkyd resins, thermosettingpolyesters such as diallyl phthalates, diallyl carbonates, styrene andmaleic anhydride-glycol adducts, and the like, and thermosettingbisphenol-epichlorohydrin resins and analogs thereof. The thermosettingbisphenolepichlorohydrin resins are especially useful where it isdesired to form a bonded abrasive mass in which the bond will set to ahardened condition at room temperature without the application of heat.

Other substances which can be used as the bond for the abrasiveparticles include shellac, natural rubber and the various syntheticrubbers, such as butadiene-styrene copolymers, butadieneacrylic nitrilecopolymers, polychloroprene and the like. An inorganic bond which can beused is an air-setting hydraulic cement such as magnesium oxychloride.

The various materials set forth above as bonding substances for theabrasive particles can be used in the form of suitable liquids,solutions, emulsions, or dispersons, depending upon the form in whichthe bonding material is most economically available.

Referring further to various figures of the drawing, Figures 1 and 2depict an abrasive disc consisting of a layer 8 of bonded granularabrasive material of substantial thickness, as for example in the orderof magnitude of M3" in thickness, adhesively secured to a textileanchoring layer 9 which in turn is adhesively bonded to a backing 10 oflatex-impregnated sisal fiber. The bonded abrasive layer 8, as shown inFigure l, has a plain continuous flat upper grinding surface 12.However, the disc can be modified, when desired, by pressing theabrasive layer with a top plunger having a gridded surface whereby theupper grinding surface 12 of the abrasive layer S is provided with aplurality of shallow annular grooves 13 and a plurality of radialgrooves 24, such a modified form of disc being illustrated in Figure 8.

Referring to Figure 7 for further details of the textile layer 9 it canbe seen that this element of the article which can be referred to as theanchoring layer or heading comprises a single course 11 of interwovenwarp or braid strands of textile fibrous material such as cotton strandswhich are spirally wound and impregnated With a latex adhesivecomposition to form an annular resilient supporting surface for thebonded abrasive layer and also as a means for mechanically anchoring thevertical pile members 14 which, as shown in Figure 7, are looped throughthe layer of interwoven textile warp strands with the free ends 15extending vertically above the anchoring layer of warp strands adistance substantially equal in thickness to the thickness of the bondedabrasive layer` As clearly pointed out these vertical pile members canconsist of any organic or inorganic fibrous or filamentary material, orcombinations of one or more organic fibrous or filamentary materialswith one another or with inorganic fibrous or filamentary materials. Thecentral or arbor portion of the abrasive disc shown is furtherreinforced by a centrally positioned disc 16 which is also oflatex-impregnated compressed sisal fibers. The abrasive disc is providedwith a mounting arbor hole 17 of suitable diameter for mounting upon thedriving spindle or shaft of the machine upon which the abrasive disc isto be used. The vertical pile members 14 not only strengthen andreinforce the bonded abrasive layer of the article throughout itsthickness but, anchored as they are in the textile base layer 9 of thearticle, they also serve to prevent disruption or dislocation of thebonded abrasive layer from its supporting base or anchoring layer duringthe use of the article. The inherently flexible and resilient characterof the backing 10 and the anchoring layer 9 provide in the finishedproduct a degree of flexibility and resilience utterly lacking in aconventional abrasive article of the grinding wheel type while at thesame time the substantial thickness of bonded abrasive material providedin the article provides a useful life far exceeding that to be found insimilar abrasive articles of the conventional coated abrasive type.

Figure 3 shows an endless abrasive belt consisting of a licxible backing18 to which is bonded a textile anchoring layer 19, which latter layercomprises a single course of interwoven textile warp or braid strandssimilar to the warp strand course embodied in the anchoring layer of thedisc of Figures l and 2. This warp strand anchoring layer is impregnatedwith a latex base adhesive which secures the anchoring layer to thebacking 18 and also provides additional strength and resilience to theanchoring layer itself. A multitude of spaced vertical pile members 20of twisted nylon cords are looped through the warp strands in a mannersuch as that shown in Figure 7 and extend above the top surface of theanchoring layer. The space between the vertical pile members 20 isfilled with a thick layer 21 of bonded abrasive material such as amixture of abrasive branules and phenolic resin bond. Before use thebelt is fiexed over a small diameter steel rod or bar to fracture thecoating of abrasive material 21 transversely of the belt in a pluralityof places 22 so that the abrasive belt can be rotated upon a drum or setof pulleys although at the same time the belt presents a substantiallycontinuous grinding surface 23 to the work to be abraded. Each fragmentof the belt however contains a number of vertical pile members which actas a reinforcement for the abrasive material and also as a means ofsecuring the separate fragments of the abrasive coating against shearingaway from the anchoring layer.

`Figure 4 shows a cup wheel which is composed of a bonded abrasive body25 reinforced by a multitude of spaced vertical pile members 26 whichare anchored in a textile anchoring layer 27 which is in turn cementedto the mounting hub 28. The mounting hub, which can be of aluminum orother metal, a molded resin body, or other suitable structural material,is provided with a screw threaded arbor hole 29 suitable for mountingthe abrading device upon a spindle or shaft. The textile anchoring'layer 27 is composed of a single course of interwoven warp or braidstrands similar .to the structure shown for the anchoring layer of theabrasive belt pictured in Figure 3. However, it may consist of one ormore courses of a coarsely woven textile fabric such as glass `fiberfabric, burlap, canvas, or the like, through 7 which the pile members 26are needled or looped to anchor them in the tex-tile layer.

Figure 5 shows a modified form of abrasive disc in which the bondedabrasive body 31 extends over the entire upper face of the disc, and inwhich the spaced vertical pile members 312 are anchored in an anchoringlayer 33 of a rubber base adhesive by which the bonded abrasive body isadhesively secured to the backing or support 34.

Figure 6 shows a still further modification of the invention in the formof an abrasive disc in which the abrasive body 36 is reinforced byvertical pile members 37 which are anchored in a base layer 38 oflatex-impregnated interwoven textile warp strands similar to thosedescribed for Figures l and 2. This particular modification of theinvention is for use in conjunction with a separately provided back-uppad or plate and therefore is not provided with a backing support as apermanent part ofthe article.

Abrasive articles of the above-illustrated type, as for example theabrasive disc shown in Figures l and 2 have been made in the followingmanner.

Example I A disc shaped base was provided consisting of an anchoringlayer or heading of a single interwoven, spinally laid course of cottonwarp strands which is impregnated with latex and thereby cemented to al/s" thick lateximpregnated sisal fiber backing. The anchoring layer hada plurality of spaced vertical pile members consisting of 50% twistedcotton fiber cording and 50% twisted Saran ber cording looped throughthe interwoven strands of the warp or braid strand course and spacedapproximately 1A from one another circumferentially and `about 1,56"from one another radially of the disc, although any other desired degreeof spacing of the pile members, either more open or closer together, maybe employed, if desired. The vertical pile members extendedapproximately Ida above the upper face of the warp strands. thusprovided was dip-sized with a low-viscosity, phenol formaldehyde liquidresin containing 1/i% of a wetting agent. One suitable phenolformaldehyde liquid resin found suitable for sizing was that known andsold by the Bakelite Corporation of Bloomfield, New Jersey, under thetrademark designation of Bakelite No. BR10190 resin. A suitable wettingagent is that known and sold under the trademark name of Span 20 byAtlas Powder Company of Wilmington, Delaware. Span 20 is otherwiseidentified as sorbitan monolaurate. disc was then placed in a die moldand an abrasive mixture of the following composition applied to the topsurface of the disc in suicient quantity to till the space between thespaced vertical pile members and levelled off iiush with the tops of thevertical pile members:

Grams LowLv-iseosity, phenol formaldehyde liquid resin A surface coatingof loose abrasive grain of the same grit size and character was appliedto the top surface of the abrasive coated disc after which the disc wasplaced under light pressure sufficient to seat the entire abrasive masstrmly. The disc wasthen placed in an oven and subjected to the followingheat treatment to mature the resinY bond: 2'4 hours at 135 F., 2 hoursat 150 F., 18 hours at 175 F., 2 hours at 185 F., 18 hours at 200 F., 2hours at 225 F., l2 hours at 250 F., 3*/2 hours at 275"V F., and 4'minutes at 375 F. The oven The upper surface of the anchoring layer asThe sized was then allowed to cool to room temperature and the `abrasivedisc removed ready for use.

Example II Abrasive discs of the type shown in Figures l and 2 have beenmade as follows: A disc shaped base of the type described in Example Iwas provided, the sole difference being that the spaced vertical pilemembers consisted entirely of twisted cottonl cording, although the pilemembers were spaced the same as those in Example l. The upper or piledsurface of the heading was first dip-sized with a low viscosity, phenolformaldehyde liquid resin such as that used for the same purpose inExample I. The sized disc was then placed in a mold `and an abrasivemixture of the following composition applied to the top surface of thedisc and rolled into the spaces or recesses between the pile members inincrements until the pile members were covered with suicientabrasive-bond mixture to bring the top surface of the mass, whenlevelled off, flush with the tops of the vertical pile members.

Grams Low viscosity, phenol formaldehyde liquid resin (such as thatknown and sold under the name Bakelite BR10190) 341 Calcium carbonate426.4 Ethylene glycol 76.7 Sorbitan monolaura'te (such as that known andsold as Span 20) a 3.8 24 grit size, fused aluminum oxide abrasivegrain-- 935 The disc was pressed at 4000 pounds per square inch andpla-ced in an oven and subjected to the following heat treatment tomature the resin bond: 6 hours at 130 F., l5 hours at 150 F., 6 hours at170 F., 2% hours at 185 F., 18 hours at 200 F., 12 hours at 225 F., 6hours at 250 F., and 3% hours at 275 F. Temperature taken to 350 F.after which the oven was allowed to cool to room temperature immediatelyand the discs removed ready for use.

The resulting abrasive disc made as above-described was used to grindwelds from metal surfaces with the following results. The disc wasoperated for a total grinding time of 69 minutes during which time atypical abrasive disc removed a total of 4345 grams of metal with a discweight loss of 335.9 grams. This can be cornpared to the resultsobtained with a conventional 24 grit size resin bonded sander disc madeby prior art methods in which the disc was operated for a total time of21 minutes before failure with a total metal stock removal of 715 grams.A cup wheel removed 3392 grams of metal in 54 minutes at a rate of 62.7grams per minute and a wheel loss of 906.5 grams at 5400 R. P. M. Thegrinding results obtained with an abrasive disc made according' toExample II as compared to the grinding results ob tained with aconventional resin bonded abrasive coated disc of the same abrasive gritsize and a resin bonded cup wheel are shown in Figure 9. As the graphshows, the life of the sander disc (see curve A of graph) isinordinately short as compared to the period of usefulness shown by anabrasive disc made according to the present invention (see curve B ofgraph) and even compares favorably with the long life of the rigidbonded cup wheel (see curve C of graph). The actual cutting rate of theabrasive disc as herein made is also noted as being remarkably high,averaging 63 grams of metal removed per minute over the entire 69minutes grinding period of the test. The remarkably longer life anddurability of discs made in accordance with the present invention ascompared to conventional abrasive coated discs heretofore used for thesame purpose is outstanding.

inasmuch as the term braided is sometimes narrowly construed to refer toa type of cording made up from a plurality of intertwined strands, it isto be pointed out that where the term braided" is used herein it isintended to refer not only to cording made up from a plurality ofintertwined strands, but also to cording made up from a single strandinterlockcd with itself in such a manner as to form a cording of braidedappearance, such as that shown in Figure 7.

Having described the invention it is desired to claim:

We claim:

1. An abrasive disc comprising a backing and a substantially continuouslayer of bonded abrasive material secured thereto, said backingcomprising a base layer, a textile ber layer comprising at least onespirally wound braided strand forming an anchoring laycr upon said baselayer and adhesively bonded thereto, and a multitude ot spaced verticalreinforcing pile members passing through said braided strand andextending into the aforesaid layer of bonded abrasive material.

2. An abrasive disc comprising a backing and a substantially continuouslayer of bonded abrasive material secured thereto, said backingcomprising a base layer of latex-impregnated sisal fiber, a textile berlayer comprising at least one spirally wound braided strand forming ananchoring layer upon said base layer and adhesively bonded thereto bymeans of a latex base adhesive, and a multitude of spaced verticalreinforcing pile members passing through said braided strand andextending into the aforesaid layer of bonded abrasive material.

3. An abrasive article comprising (a) a backing, (b) an anchoring layercomprising at least one course of textile iber braided strand adhesivelyimpregnated and bonded to said backing by means of a ilexible rubberbase adhesive and containing a plurality of vertically extending spacedtextile ber reinforcing pile members secured therein with the free endsprojecting above the top surface of said anchoring layer, and (c) alayer of resin-bonded abrasive material imposed upon said anchoringlayer and filling the space between said spaced pile members so as toform a substantially continuous grinding face.

4. An abrasive article comprising a composite back ing comprising aexible sheet backing material and an anchorng layer of textile braidedstrand impregnated with a resilient latex base adhesive, said anchoringlayer having a plurality of spaced reinforcing pile members anchoredtherein with the free ends extending vertically therefrom, `and asubstantially continuous layer of phenolic resin-bonded granularabrasive material bonded to said anchoring layer and of a thickness atleast coextensivc` with the height of said pile members.

5. An abrasive article comprising a composite backing comprising aflexible sheet backing material and an anchoring layer of interwoventextile material impregnated with a resilient latex base adhesive, saidanchoring layer having a plurality of spaced reinforcing pile membersanchored therein with the free ends extending vertically therefrom, anda substantially continuous layer of resinbonded granular abrasivematerial bonded t-o said anchoring layer and of a thickness at leastcoextensive with the height of said pile members.

6. An abrasive article according to claim 5 in which the verticalreinforcing pile members are nylon cords and the textile material is acotton fabric.

7. An abrasive article according to claim 4 in which 5% to 95% of saidpile members are of heat resistant organic thermoplastic material and to5% of said pile members are of natural organic fibrous material.

8. An abrasive disc comprising a backing, a substantially continuouslayer of bonded abrasive material secured thereto, and a multitude ofspaced vertical reinforcing pile members extending into the layer ofbonded abrasive material, said backing comprising a single spirallywound braided strand, said pile members passing through said braidedstrand.

9. An abrasive disc comprising a backing, a substantially continuouslayer of bonded abrasive material secured thereto, and a multitude ofvertical reinforcing pile members extending into the layer of bondedabrasive material, said backing comprising at least one spirally woundbraided strand, said pile members being spaced approximately 1A inchfrom one another circumferentially and about 1,46 inch from one anotherradially of the disc and passing through said strand.

References Cited in the tile of this patent UNITED STATES PATENTS1,077,143 Krug Oct. 28, 1913 1,209,831 Gardner Dec. 26, 1916 1,529,410Doermann Mar. 10, 1925 1,775,631 Carlton Sept. 16, 1930 1,822,856 DirkesSept. 8, 1931 1,850,413 Porte Mar. 22, 1932 1,899,959 Happ Mar. 7, 19331,961,911 Pusch June 5, 1934 2,001,911 Wooddell et al May 25. 19352,013,925 Okie Sept. 10, 1935 2,071,563 Newcomb et al Feb. 23, 19372,085,211 Budds et al June 29, 1937 2,115,897 Wooddell et al. May 3,1938 2,137,305 Perazzoli Nov. 22, 1938 2,186,001 Bartling Jan. 9, 19402,189,754 Cherrington Feb. 13, 1940 2,232,389 Jurkat Feb. 18, 19412,328,998 Radford Sept. 7, 1943 2,347,244 Colt et al Apr. 25, 19442,520,763 Goepfert et al Aug. 29, 1950 2,590,697 Grove Mar. 25, 1952

3. AN ABRASIVE ARTICLE COMPRISING (A) A BACKING, (B) AN ANCHORING LAYERCOMPRISING AT LEAST ONE COURSE OF TEXTILE FIBER BRAIDED STRANDADHESIVELY IMPREGNATED AND BONDED TO SAID BACKING BY MEANS OF A FLEXIBLERUBBER BASE ADHESIVE AND CONTAINING A PLURALITY OF VERTICALLY EXTENDINGSPACED TEXTILE FIBER REINFORCING PILE MEMBERS SECURED THEREIN WITH THEFREE ENDS PROJECTING ABOVE THE TOP SURFACE OF SAID ANCHORING LAYER, AND(C) A LAYER OF RESIN-BONDED ABRASIVE MATERIAL IMPOSED UPON SAIDANCHORING LAYER AND FILLING THE SPACE BETWEEN SAID SPACED PILE MEMBERSSO AS TO FORM A SUBSTANTIALLY CONTINUOUS GRINDING FACE.